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Pressure

cmH₂OtommHg

Convert centimetres of water column (cmH₂O) to millimetres of mercury (mmHg).

Factor1 cmH₂O = 0.7355591 mmHg

Converter

cmH₂O

Accepts numbers or expressions, e.g. 150 + 14.7

Result
73.5559mmHg

Rendered to 6 significant figures.

Formula

Formula
mmHg = cmH₂O × 0.7355591

Multiply any value in centimetres of water column by 0.7355591 to obtain the value in millimetres of mercury.

Worked example

Convert 100 cmH₂O to mmHg.

  1. 01Start with 100 cmH₂O.
  2. 02Multiply by the conversion factor: 100 × 0.7355591 = 73.5559 mmHg.
Result100 cmH₂O = 73.5559 mmHg

Conversion table

cmH₂OmmHg
10.73556
21.4711
53.6778
107.3556
2014.711
5036.778
10073.556
200147.11
500367.78
1000735.56

Reference values rounded to 5 significant figures for display.

FAQ

What is the conversion factor from cmH₂O to mmHg?
1 cmH₂O equals 0.7355591 mmHg. To convert, multiply the value in centimetres of water column by 0.7355591.
How do I convert 1 cmH₂O to mmHg?
1 cmH₂O = 0.735559 mmHg. For any value, multiply by 0.7355591.
How do I convert mmHg back to cmH₂O?
Divide by the same factor — or equivalently, multiply by 1.35951. So 1 mmHg = 1.35951 cmH₂O.
When would I need to convert centimetre of water column to millimetre of mercury?
Pressure conversions between cmH₂O and mmHg are common when working with mixed-vendor instrumentation, when piping codes use different units to process datasheets, or when converting field readings into SI for hydraulic calculations.
Is the conversion exact?
The factor shown is precise to at least 7 significant figures. For most process-engineering work this is far better than instrument accuracy. For metrology or trade applications, refer to the relevant national standard (NIST, BIPM, ISO 80000).

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